There are many kinds of clamps used to grip objects. One kind of clamp, often referred to as a spring clamp, is provided with a spring that forces the jaws of the clamp towards one another. In order to use a spring clamp, one squeezes the handles of the clamp together, wherein the squeezing action works against the force of the spring, thereby spreading the clamp jaws apart and permitting insertion of a workpiece or workpieces between the jaws. Upon release of the squeezing force, the spring forces the jaws against the workpiece or workpieces.
A variation of the spring clamp is known as an adjustable clamp. In an adjustable clamp, a spring is provided that forces the jaws of the clamp away from one another. When a user squeezes the handles of the adjustable clamp towards one another, the clamp jaws are gradually brought closer to one another until they finally abut each other. A ratchet mechanism is provided that works against the force of the spring and arrests the clamping jaws at discrete positions as they approach one another. The ratchet mechanism thus permits adjusting and maintaining the clamping jaws at any desired position as the handles of the adjustable clamp are squeezed together. In this manner, the jaws may be clamped against a workpiece or workpieces placed between the jaws.
Bar clamps generally comprise a pair of clamping jaws that slide along a bar. A workpiece may be clamped between the jaws by abutting the jaws against opposite sides of the workpiece, and then tightening the jaws against the workpiece, such as by repetitive squeezing of a hand-held trigger mechanism.
The bar clamp may also be used to spread objects apart. This may be accomplished in some bar clamps by turning around the clamping jaws 180°, which reverses the advancing movement of the jaws along the bar towards each other into a retreating movement away from each other. The objects may be spread apart by abutting the jaws against the appropriate surfaces of the objects, and then moving the jaws in the spreading direction, such as by repetitive squeezing of the hand-held trigger mechanism.